Abstract: In order to achieve the impedance matching of wideband and stability, an impedance converter with a combination of parallel coupling lines and gradual microstrip lines is used to complete the required conversion between unequal impedance by designing an impedance converter with broad band and good return loss through electromagnetic simulation software.The influence of the structure on the return loss is discussed. The relative bandwidth of the return loss less than-10 dB is 70%（1350 ～ 2750 MHz）, and the return loss value at the center frequency 2.2 GHz is negative 17 dB.Compared with the traditional stepped impedance converter, it has better in-band flatness and stability, and is suitable for multi-frequency antennas and power amplifiers.